1. Field of the Invention
The invention relates to a flame retardant and a polymer composition using the same, such as thermosetting composition, thermosetting inkjet ink, photo-curable composition, and photo-curable inkjet ink, in particular, to an inkjet ink for manufacturing liquid crystal display (LCD) devices, electroluminance display devices, printed circuit boards, and so on. Furthermore, the invention relates to a flame-retardant cured film formed by an inkjet ink, an electronic circuit board with a flame-retardant cured film formed thereon, and an electronic component with the electronic circuit board.
2. Description of Related Art
Generally, in order to ensure safety, the electronic circuit boards are required to use flame-retardant materials. Various bromides have been used previously for flame retardancy. However, due to the Dioxin problem occurring during combustion, a flame retardant free of bromides is needed. Currently, electronic components are required to have an increased heat resistance, and thus a flame retardant having a reactive functional group is needed. In this case, a variety of reactive flame retardants have been proposed (with reference to, for example, Japanese Laid-Open Patent Applications S60-161993, 2001-106766, 2001-213889, 2002-121245, and 2004-91683, and so on). However, the flame retardants described in the above patents are compounds obtained from the reaction of phosphorus-containing compounds and double bond of acryl; and thus, the variation range of the materials is rather narrow, which is difficult to balance among adhesion, chemical resistance, heat resistance, and elasticity required for the electronic circuit boards. On the other aspect, in recent years, when an electronic circuit board is being manufactured, an ink-jet printing process has been proposed as a method for forming a patterned cured film. The ink-jet printing process can provide the advantages of lower capital investment on equipments and higher material utilization efficiency, and a composition (an ink-jet ink) used in the method has also been proposed (with reference to, for example, Japanese Laid-Open Patent Application 2003-302642, WO 2004/099272 pamphlet, Japanese Laid-Open Patent Applications 2006-282757, and 2006-307152).
However, the cured films formed by these inkjet inks do not have sufficient flame retardancy.